Control system



c. J. WERNE-ZR 2,095,579

CONTROL SYSTEM Filed Sept; 6, 1934 2 Sheets-Shem. 1

Oct. 12, 1937.

INVENTOR Calvin J Mrner ATTORNEYS Oct. 12, 1937. c. J. WERNER 2,095,579

CONTROL SYSTEM F1led Sept. 6, 1934 2 Sheets-Sheet 2 Ila" Y //5 /02 v /M 92 V //2 250 224 226 /2.2- 3; may... on

} INVENTOR v @Mww ATTORNEYS Patented Oct. 12, 1 937.

PATENT OFFICE 2,095,519 I CONTROL SYSTEM Calvin J. Werner, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Application September 6, 1934, Serial No. 142,941 11 Claims. (01. 112.419),

This invention relates to the control of-electrical circuits, and more particularly toa control system for controlling .the circuits of, an electric motor responsive to a thermal-responsive 5 device.

An object of this invention is to provide a control system incorporating a thermal-responsive switch having more than one set of contacts controlled by a thermal-responsive element, said switch being so constructed and arranged that a plurality of circuits are controlled in a predetermined sequence by the thermal-responsive element.

- Another object of thisinvention is to provide a control system including a switch responsive to a single thermal-responsive element that controls the starting and running circuits of a motor and also provides overload protection for the motor.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of one form of the present invention is clearly shown.

In the drawings:

Figs. 1, 2 and 3.are circuit diagrams of motor control circuits embodying preferred forms of the present invention.

. Figs. 4 and 5 are circuit diagrams of motor control circuits embodying modified forms of the present invention.

The switch disclosed in the circuits shown in M Figs. 1, 2 and 3 is shown in detail in my copending application Serial No. 39,293 which is adivision of this application. Only the essential parts of the switch are shown and described in this application. That is, a movable support mem- 40 her 24 is pivotally mounted on a pivot shaft 32.

A spring 46 has one end anchored to a connecting portion 42 of the movable support member 24; and has its other end anchored to membering pin 46. The spring 40, being a tension spring, 45 biases or urges the movable support member in one direction about the pivot shaft 32. A thermal responsive element 56, that preferably comprises a wire having a relatively high temperature coefllcient of expansion, has one end connected to a lug 58 on the movable support member 24, that is preferably located on the opposite side of the pivot shaft 32 from the spring 40. The other end of the thermal responsive element is fixedly anchored. Insulating stationary con- 5 tact support members 14 and 16 have stationary contacts 90 and 92 respectively secured there o.

Movable contacts III! and H2 are pivotally supported by the movable support member 24 and have contact points H6 and H6 respectively secured thereto in alignment for engagement with the stationary contacts and 92 respectively. 5 Springs I26 and I22 have an end connected to the movable contact members III! and H2 respectively and their other erids anchored to lugs I44 and I46 respectively, which lugs are preferably integral with the movable support member 10 24. Stop members I62 and I64 are provided for arresting movement of the contacts III) and H2 respectively away from the contacts 90 and 92. With particular reference to Fig. 1, a motor I56 has a main field winding I52, a starting or 15 auxiliary field winding I54, and a rotor I56 that is preferably of the squirrel cage type. One end of the main field winding I62 and an end of the auxiliary field winding I64 are connected to a power supply line wire I68. The other end of the 20 main field winding I62 is connected to one end of the thermal responsive element 56; and the otherend of the auxiliary field winding I54 is connected to the stationary contact 92. The other end of the thermal-responsive element 56 is 25 grounded to the auxiliary support member 24, to which the movable contacts IIII and H2 are also electrically connected. The stationary contact 96 is connected to a power supply line wire with particular reference to Fig. 2, a motor I62 has a main field winding I64, a starting or auxiliary field winding I66 and a rotor I68 that is preferably of the squirrel cage type. One end of the main field winding I64 and an end of the 5 auxiliary field winding I66 are connected to a power supply line wire H0. The other end of the main field winding I64 is grounded to the auxiliary support member 24, to which the movable contacts IlIIand II2 are also electrically 40 connected, The other end of the auxiliary field winding I66 is connected to the stationary contact 92. Another power supply line wire I12 is connected to one end of the thermal-responsive element 56. The other end of the thermal- 45 responsive element is insulated from the auxiliary support member 24, in this form, and is connected to the stationary contact 90. The insulation of the end of the thermal-responsive element from the auxiliary support member is accomplished, in this form, by making the member 58 of insulating material.

With particular reference to Fig. 3, a motor- I60 has a main field winding I82, 9. starting or auxilifie y field winding I84, and a rotor I86 that is preiwith an a.

7 support member 26,

erably of the squirrel cage type. One end of the main field winding I82 and an end of the auxiliary field winding I82 the movable contacts connected.

Although the most nearly effects the desired control, for accomplishing the control of the motor. In the form shown on Fig. l, the thermal-responsive element is connected in series with the main field Winding I52, so that the control is effected by the main contacts 92 and H8 are disengaged.

With particular reference to Fig. 4, parts bear-, 7 ing reference numerals similar to those previously parts that perform similar connected to a power supply line wire m. The

other end of the main field winding202 is connected to another power supply line wire 252 and to the stationary contact 92. The other end of the auxiliary field winding 222 is connected to an added thereto. A motor 220 has a main field winding 222, an auxiliary field winding 2261, a third winding 226, and a rotor 228 that is preferably of the squirrel cage type. One endof the main field winding 222 and an end of the auxiliary winding 224 are connected to a power supply line wire 23!]. The other end of the main field winding 222 is connected to both of the stationary:

- element 56a. sponsive element 56a is connected to the auxiliary the contacts aooaova contacts 90 and 92. The other end of the auxiliary field winding 224i is connected to one end of the third winding 226 and to the auxiliary support member 26. The other end of the third winding 226 is connected to one end of the thermal-responsive element 56, the responsive element is also connected to the auxiliary support member 26, which auxiliary support member is electrically connected to the movable contact II2. Another power supply line wire 232 is connected to one end of the thermal-responsive The other end of the thermal-re support member 2 3a that is pivoted at 32c and.

biased in one direction by a spring 20a to arately control the movable contact II 0.

In the preferred form of the switch, the movable support member 22 and the stationary contact carrying members M and 76, as well as the pivotal supports for the contacts II 0 and H2, are so disposed that the angular relations of the contacts I I0 and H2 to the movable support member 24 and the action lines of the springs I 20 and I22 difler when the contacts II 0 and H2 are in their normal engaged or disengaged positions. This difference in angular relation effects operation of'the contacts III] and II 2 at different times in response to the movement of the movable support member 22 about the pivot shaft I22 and I22 are so disposed that septhe particular form shown,

angular relation of the movable contact H2 to the auxiliary support member 241 and the action line of the spring I22 is such that the action line bf the spring I22 crosses the pivotal axis of the contact H2 before the action line of the spring I20 crosses the pivotal axis of the contact I I0. Hence, in this form, it takes a lesser movement of the movable support member 24 to effect actuation of the contact II2 than it does to efiect actuation of the contact III]. When the contacts H0 and H2 move toward the stationary contacts 90 and 92 respectively, the stationary contacts arrest the motion of the movable 'contacts in that direction. When the movable contacts move in the opposite direction, the motion thereof is arrested by the stops I22 and I22.

The spring ill biases the movable support member 22 in a counterclockwise direction, as viewed in Figs. 1 to 3 inclusive. When the auxiliary support member moves in that direction under the influence of the spring 60, disengagement of the contacts 92 and H8 is first efi'ected, and then 90 and H6 are disengaged. However, the positionand motion of the movable support member 24 are controlled by the thermalresponsive element 56. The efiective length of that element is preferably so adjusted that the contacts are normally engaged, so that when the thermal-responsive element expands due to a change of the temperature thereof, the force of the spring 20 moves the movable support member 22 to effect disengagement of one or both sets of contacts, depending upon the degree of expansion of the thermal-responsive element 56. Upon return of the temperature of the thermal-responsive element to normal, the contraction of that element actuates the movable support memother end of which thermal ber 24 inthe opposite direction to eflect en gement of the contacts:

In the operation of the circuit shown in Fig. 1,

when a source of current is connected to the power supply line wires I56 and I60, and the contacts 66 and H6 and 62 mally engaged, the main field winding is connected across the power supply line wires I56 and I-60 through the contacts 90 and I I6 and the thermalresponsive element 66. The auxiliary field winding I54 is connected across the power supply tively high temperature coemcient of expansion expands due to the heat produced by the current flow through the resistance thereof, and the expansion effected in normal operation of the motor and switch effects disengagement of the contacts 62 and H6 to open the circuit to the auxiliary field winding I54. This establishes the running circuit. If any abnormal condition, such as an excessive overload on the motor occurs, the current flow through the main field winding I62 and the thermal-responsive element 56 increases the temperature of the thermal-responsive element by an amount disengagement of the contacts 90 and H6. This opens the circuit to the main field winding I52 to stop the motor. When the temperature of the thermal-responsive element 56 returns toward normal, the thermal-responsive element contracts to first effect engagement of the contacts 92 and H6, and then to effect engagement of the contacts 60 and "6. It is preferable that the contacts 62 and III! engage, prior to the engagement I I6, so that the main field winding alone will not beconnected across the power supply line when the motor is stopped.

Theoperation of the circuit shown in Fig. 2 is similar to that shown in Fig. 1, except that the temperature of the thermal-responsive element is controlled by the current through both the main field winding I64 and the auxiliary field winding I66 when the contacts are closed, and is controlled by the .current through only the main field winding I64 when the contacts 92 and '8 are disengaged and the motor is running.

The operation of the circuit shown in Fig. 3 is similar to that of the circuit shown in Fig. 2, except that in this circuit either set of contacts closes the circuit from the power supply line to one of the windings independent set of contacts. Hence, to avoid having one of the field windings connected across the power supply line when the motor is stopped, both sets of contacts must close at substantially the same instant; while in the circuit shown in Fig. 2 the circuit to the auxiliary field winding I66 is estabiished through both sets of contacts. Hence, in the circuit of Fig. 2, it is preferable that the contacts 92 and H8 engage prior to the engagement of the contacts 90 and H6 as explained for Fig. 1.

In the operation of the circuit shown in Fig. 4, a source of current is connected to the motor through the power supply line wires 2I0 and 2I2. The third winding 206 may be electromagneticall-y coupled with one or 202 and 204, but is preferably electromagnetically coupled with the auxiliary field winding 204 and the rotor so that a voltage is induced in the third winding 206 by virtue of that electromagnetical and H6 are norsufficient to efiect of the. other both of the field windings support coupling. The electro-magnet coupling with the rotor eii'ects an increase in the voltage induced in the third winding 206 as the rotor speed increases. I The contacts 62 and .6 are normally engaged. Then, since thethermal-responsive element 66 is connected across-the third winding 206, the voltage induced in the third winding 266 causes a current flow through the sponsive element to heat the thermal-responsive element. Heating of the thermal-responsive element effects expansion thereof, so that the spring 40 actuates the auxiliary support member 24 by an amount such that the action line of the spring I22 crosses the pivotal axis of the contact II2 to effect disengagement of the contact. This establishes the running circuit of the motor. The voltage induced in the third winding from the main field winding or the rotor, or both, but preferably only the latter, causes a current flow through the thermal-responsive element, so that the contacts remain open while the motor is operating normal- 1y. 'When the motor is stopped by disconnecting the current source from the power supply line wires, the thermal-responsive element cools and contracts, so that engagement of the contacts is again effected. Also, if the motor speed is reduced by a sufllcient decrease in line voltage or an abnormal load, the reduction in ,the induced voltage in the third winding permits the thermalresponsive element to cool sufilciently to effect reengagement of the contac s. I

In the operation of the circuit shown in Fig. 5, the control of the starting and running circuits of the motor is eiIected in substantially the same manner as that described for the circuit in Fig. 4. In this circuit, however, an overload protection is provided by an additional switch having a thermal-responsive element 56a that preferably requires a greater current flow therethrough to effect operation of the switch, than does the thermal-responsive element 66. In this circuit, when the current flow through the thermalresponsive element 66a is abnormal due to some abnormal condition such as an excessive overload on the motor, disengagement of the contacts such as 90 and H6 is effected to open the circuit to the main field winding 222 and stop the motor.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. In combination, a motor having a rotor and starting and running circuits including main and auxiliary field windings, and a switch for controlling the starting and running circuits, said switch comprising a pivotally mounted movable support member, a spring biasing the movable support member in one direction, a thermal-responsive e ement connected in series with one of the field windings for controlling the movement of the movable support member, a stationary contact,

and a cooperating movable contact controlled.

by movement of the movable support member for controlling the starting and running circuits of the motor.

2. In combination, a motor having a rotor and starting and running circuits including main and auxiliary field windings, and a switch for controlling the starting and running circuits, said switch comprising a pivotally mounted movable member, a spring biasing the movable support member in one direction, a thermalresponsive element connected in series with the thermal-re- 0f the movable support member, a stationary contact, and a cooperating movable contact controlled by movement of the movable support member for controlling the starting and running circuits of the motor.

3. In combination, a motor having a rotor and starting and running circuits including main and auxiliary field windings, and a switch for controlling the starting and running circuits, said switch comprising a pivotally mounted movable support member, aspring biasing the movable support member in one direction, a thermal-responsive element connected in series with both of the field windings for controlling the movement of the movable support member, a stationary contact, and a cooperating movable contact controlled by movement of the movable support member for controlling the starting and running circuits of the motor.

4. In combination, a motor having a rotor'and starting and running circuits including main and auxiliary field windings, and a switch for controlbeing connected in series windings, and a thermal-responsive element con- .nected in series with at least one of the field windings for controlling the position of the movable support member to eil'ect control of the sets of contacts.

ment of the movable support member to eflect control of the contacts. 6. In combination,

2,095,579 I main field winding. for controlling the movement '7. In combination, a motor having a rotor and starting and running circuits including main and auxiliary field windings, a power supply circuit for the motor, a switch having a plurality of sets of contacts, one set of contacts controlling the starting circuit of the motor, another set of said contacts opening the power supply circuit responsive to an abnormal condition, said contacts autoininedsequence while the abnormal condition exists,'and a single thermal-responsive element for controlling the switch.

8. In combination, a motor having a rotor and starting and running circuits including main and auxiliary field windings, a power supply'circuit of the motor, another set of said contacts opening the power supply circuit responalways reengaging at the same time or before the reengagement of the contacts that open the power supply circuit, and a thermal-responsive element for controlling the switch.

9. In combination, a power supply circuit, a

10. In combination, a motor including a rotor and windings, and having starting and running circuits and ment of the movable support member in the other direction.

11. In combination, a motor having a power input circuit, a rotor and starting and running circuits including main and auxiliary field windings, and a switch including a spring and a single thermal-responsive element and having various positions for controlling the circuit of the auxiliaryfield winding'to'control the starting circuit CALVIN J. WERNER. 

